President Bush (r.) stands alongside his nominee for the Supreme Court, John G. Roberts Jr., after having breakfast at the White House Wednesday, July 20, 2005 in Washington DC. Mr. Roberts, Bush's first nominee to the Supreme Court, is a rock-solid conservative who had won broad support from both parties. Charles Dharapak/AP/File

President Ronald Reagan gestures during a news conference at the White House where he announced the nomination of Antonin Scalia (l.) to the Supreme Court on June 17, 1986. Chief Justice William Rehnquist is at right. Widely regarded as the court's leading intellectual and often described as a gentleman, Mr. Scalia also is the court's most provocative, and sometimes petulant, justice. Ron Edmonds/AP/File

Supreme Court Justice Anthony Kennedy was appointed by President Ronald Reagan in 1988 to replace Lewis Powell Jr. after Robert Bork was rejected by the Senate and Douglas Ginsberg withdrew. Mr. Kennedy has been known as the court's swing vote during politically charged decisions, leaning to the right more often than not. However, he is not ideological, and looks at each case individually. Charles Dharapak/AP/File

Associate Justice Clarence Thomas succeeded Thurgood Marshall in 1991 after prevailing through confirmation hearings that had become embroiled in a sexual harassment controversy. Mr. Thomas is known as one of the most conservative justices. He maintains silence during oral arguments and has said, 'One thing I’ve demonstrated often in 16 years is you can do this job without asking a single question.' Manuel Balce Ceneta/AP/File

Associate Justice Ruth Bader Ginsburg was appointed by President Bill Clinton in 1993. Despite being denied a clerkship position by Justice Felix Frankfurter in 1960 because of her gender, Ms. Ginsburg went on to be the second woman serve on the Court after Sandra Day O'Connor. Considered to be a liberal, she spent much of her pre-Court career as an advocate of women's rights. Jim Young/Reuters

Associate Justice Stephen G. Breyer was appointed by President Bill Clinton in 1994. Mr. Breyer has consistently voted in support of abortion rights and is in favor of gun control. He attended Oxford University, is married to a member of the British aristocracy, and is fluent in French. Jim Young/Reuters

Supreme Court Associate Justice Samuel A. Alito, Jr. listens during an event at Roger Williams University Law School in Bristol, RI. Justice Alito has been described as a conservative jurist with a libertarian streak. He was appointed by President George W. Bush in 2006 and has been a member of the Federalist Society, a group of conservatives and libertarian lawyers and legal students interested in conservative legal theory. Stephan Savoia/AP/File

Supreme Court nominee Sonia Sotomayor testifies on Capitol Hill in Washington, D.C., before the Senate Judiciary Committee in 2009. Associate Justice Sotomayor hails from Bronx, N.Y. and is the first Hispanic justice to serve on the Court. Ms. Sotomayor was appointed by President Barack Obama in 2009. She attended Princeton on full scholarship and has said she was inspired to pursue a legal career and become a judge by watching the Perry Mason television series. Charles Dharapak/AP/File

President Obama applauds Elena Kagan during a ceremony in the East Room of the White House in Washington on Aug. 6, 2010, after her confirmation as Supreme Court justice by the Senate. Ms. Kagan is the first justice appointed without any prior experience as a judge since William Rehnquist in 1972. She served as Solicitor General to President Obama from 2009 - 2010. Pablo Martinez Monsivais/AP/File